a–d , Structural integrity in regions within ( a ) VTOC (FG), ( b ) PPC (IPS), ( c ) PFC [DLPFC, VLPFC, and pre/primary motor cortex (PMC)], and ( d ) visual cortex (cuneus) predicts longitudinal gains in numerical abilities. Children with higher volume in these regions at age 8 had steeper growth curves from childhood to adolescence. GMV, Gray matter volume.